"Forsyth de Fronsac" is an entirely fabricated name. No such name existed, except in the mind and writings of Frederick Gilman Forsyth, who called himself "Frédéric Forsyth de Fronsac", and often published as "F.G. Forsyth", or, simply, "Forsyth de Fronsac" (his appropriated alias name).

Forsyth was the author of numerous books, published between 1878 and 1925, including fraudulent genealogies claiming specific , yet false, ancestral connection to, for instance, Acadian Governor Nicolas Denys and English Parliamentarian Henry Hamilton, and so to their illustrious ancestors.

"From 1878 until his death in 1925, he published more than 30 books and articles in which he speaks at length about the Aryan Order and the College of Arms... Studies reveal that Forsyth de Fronsac advocated a monarchist, antidemocratic and racist-tinged ideology that underlined all of his actions, both in the United States and Canada... The same blend of wild imagination and absolute disregard for consistency pervades the whole works of Forsyth de Fronsac, whether he revisits his life, the story of his family, or the history of North America..." The Aryan Order of America and the College of Arms of Canada 1880-1937', by Yves Drolet; Montreal, Canada, 2015, p. 25.

Forsyth found a partner in crime in Aryan Order of America member and fellow author of false lineages, Genealogist Charles Henry Browning, to further perpetrate fraudulent lineage. (See Category: Charles Henry Browning Fraud).

Falsified genealogies and other historical data include, in whole or part, most notably:

* Memorial of the family of Forsyth de Fronsac, by Frédéric Gregory Forsyth de Fronsac; S.J. Parkhill & Co.; Boston, Mass, USA; 1903,
* A genealogical record : Forsyth of Nydie, by Forsyth de Fronsac; Henkel and Co.; Virginia, USA; 1888.
* Rise of the United Empire Loyalists: A Sketch of American History, by Frederic Gregory Forsyth; British Whig Publishing Company; Kingston, Ont., Canada; 1906.